Current interrupter



June 30, 1942. HANLEY 2,288,398

CURRENT INTERRUPTER Filed May 7, 1941 25 a it? /2 /7 e T e 29 L; /a 7 JILL INVENTOR.

BY g I 2/ Patented June 30, 1942 CURRENT INTERRUPTER John A. Hanley, Noroton, Conn., assignor to Gillette Safety Razor Company, Boston, Mass., a

corporation of Delaware Application May '7, 1941, Serial No. 392,196

Claims.

This invention consists in a new and improved current interrupter for use in motors of the magnetic type operating on alternating or direct current. It is articularly useful in small motors used in dry shavers and the like but is not limited to them in its field of use.

In motors of this type as heretofore constructed tungsten contact points have been employed and these have been carried by levers, one or both of which are moved to make and break an electric circuit at the proper time with relation to the position of the armature to the magnetized field poles. Such mechanism has proved to be noisy on account of the cam action of the levers and the hammering effect of the points as well as the noise of the spark on breaking the circuit. A further objection to the prior construction is that since the spark is free and unenclosed it is likely to set up high frequency Waves effecting radio apparatus. Moreover, the uniform operation of motors of this type depends upon the critical adjustment of the points and gap. The points wear away under the continued arcing which occurs in use and the power and speed of the motor is consequently impaired because of this condition. Frequent compensating adjustments have, therefore, been necessary to keep the motor in satisfactory operating condition.

In the device of my invention as herein disclosed current interruption is obtained by the synchronous oscillation of a metallic cylinder or other appropriate conductive enclosure containing a freely movable conductor and having sealed insulated contacts or electrodes spaced therein upon opposite sides of the conductor. The operation of the device depends upon the inertia of the conductor which tends to hold it at rest while the cylinder is moved. As this is oscillated from side to side the intermediate conductor therein, because of its tendency to remain motionless or to delay in its motion with respect to the cylinder, makes alternate contacts with one or other of the insulated electrodes and so intermittently includes the metallic cylinder in the circuit.

The interrupter of my invention is herein shown as carried at one end of a rocker of new and improved form which is oscillated in fixed timed relation to the armature; as for example.

by an accentric or a cam on the armature shaft shaped so that contact is established when the armature is in the proper position with respect to the field poles. An important feature of my invention consists in making the rocker as an at one end to provide for itself a wide stiff bear ing and in some instances so designed that the end which carries the interrupter may take on a whip when the rocker is oscillated. Thus the cam actuation of the rocker may be reduced in amplitude since the movement of the interrupter itself is made up of two components, that is to say, movement due directly to cam actuation and in addition movement due to the whip of the rocker.

Another feature of my invention consists in an improved movable conductor within the enclosure of the interrupter. In my prior application Serial Number 371,899, filed December 27, 1940, is disclosed an interrupter having a solid metal slug movable in electrical contact with a metal tube. In order to insure continuous contact between this movable member and the tube I now propose to form the conductor in two parts; for example, as a cylindrical slug having a transversely movable insert therein which tends of its own accord as well as by reason of the weight of the slug to maintain at all times electric contact with the tube or cylinder of the interrupter. In addition to providing a reliable and continuous contact this construction facilitates free movement of the conductor within its enclosing tube, or free movement of the tube while the conductor remains at rest by reason of its inertia.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, in which:

Fig. l is a view of the motor in front elevation;

Fig. 2 is a fragmentary view in side elevation;

Fig. 3 is a view of the interrupter in longitudinal section and on an enlarged scale; and

Fig. 4 is a corresponding View in cross-section.

My invention is herein shown as embodied in a motor designed especially for use in a dry shaver although the invention is in no way limited to this or to any particular type of motor but is useful wherever a current interrupter may be required and movement of the interrupter can be obtained.

The illustrated motor includes a laminated field magnet l0, substantially U-shaped in outline and provided at its bend with field windings in a coil II. The free ends of the magnet are secured to a frame I2 which is approximately triangular in contour and has an upwardly proarm of resilient sheet metal, U-shaped in contour jecting bracket l3 in which is journaled a transverse shaft [4. Journaled on the shaft [4 is an operating lever shaped at its upper end to reciprocate the cutter of a dry shaver, or for similar duty. At its lower end, not shown, the operating lever I5 embraces an eccentric on the armature shaft which is journaled in the frame 12. A segmental armature 22 is carried by the armature shaft and arranged to rotate between the poles of the field magnet 10. The construction heretofore described forms no part of my invention and is merely typical of a motor, such as is contemplated in connection with my invention.

Pivotally mounted upon the opposite face of the frame I2 from the operating arm [5 is a flexible rocker member [6, herein shown as an arm arranged to oscillate about the axis of a threaded pin 23 projecting from the frame I2. The rocker arm is is constructed of thin resilient sheet metal and at its upper end is bent forwardly and then downwardly forming a tongue 'Il disposed substantially parallel to the body of the arm and spaced from it so as to form with the body of the arm a wide bearing. It is also held under slight resilient pressure by the screw head of the pin 23 so that the arm as a whole is confined to oscillatory movement in a pre-determined plane. The arm is apertured midway between its ends to receive the outer end of the armature shaft 28 and an eccentric 2| therein by which the arm is oscillated. The side edges of the aperture are turned out in parallel flanges to afford substantial bearing area for the cam 2|. Below its aperture the rocker arm is provided with a 90 twist l8 and below that it is formed into a retaining loop E9 in which the interrupter tube is carried. The twist I8 is provided in order to reduce the stiffness of the arm in this section and permit its lower tube-carrying end to take on a whip when the rocker arm is oscillated at high speed. As already noted the provision of this flexible section in the rocker arm permits the throw of the eccentric to be reduced while full amplitude of movement occurs in the end of the rocker by reason of the whip which supplements its movement under the actuation of the cam.

The interrupter itself comprises a tube or tubular enclosure 30 of metal closed by insulating plugs 3| permanently secured in both ends between a circumferential corrugation and the slightly inturned or spun-over end of the tube.

Each plug 3| is provided with an electrode comprising a metal stem 32 having an inner contact face 33 of tungsten or other hard contact metal.

Between the hardened faces of the electrodes thus provided is located a freely movable metallic slug 34 having a hardened contact face of tungsten 35 or the like on each end opposite to the stationary faces 33 and being provided with a tapering recess in its lower face in which is placed a loose metal insert 36. The slug 34 fits within the tube 30 with just sufficient clearance to permit its free movement. The insert 36 is also freely movable in its recess although it tends to be forced outwardly by the taper of the walls of the recess and thus is maintained at all times in metallic and electro-conductive contact with the walls of the tube 30.

The specific arrangement of the motor circuit is of secondary importance only, so long as current delivered to the tube 3i] through the clamp I9 is taken out through one end or the other as they are moved alternately into contact with the intermediate conductor. As herein shown the two electrodes are connected by a common lead 21 looped below the tube 36, and that side of the circuit is then connected to one terminal of the field coils and one terminal of a condenser 29 which is mounted about the coil II. The clamp is, which is in conductive engagement with the tube 39, is connected to the other field coil terminal and to the other condenser terminal by a connection enclosed in an insulating tube 28 and extending from the downturned tongue ll of the rocker. Service connections are made to the proper terminals of the respective coils.

When the armature shaft is spun by the starting Wheel provided for that purpose one electrode is brought into contact with the intermediate conductor 34 and current flows through the field magnet until the armature has rotated nearly to its straight across position. Thereupon the cam 2| throws the rocker in the other direction and the current is interrupted until the conductor 34 is engaged by the electrode at the opposite end of the tube 3|. When this occurs connections are established with the current flowing in the coils in the same direction as before its interruption and the armature is again turned into its straight across; position having advanced in the meantime.

The oscillation of the arm I 6 is adjusted so that contact is established when the armature position with respect to the field poles is other than straight across and broken when straight across. The time of contact and open contact can be adjusted by the distance of travel of the movable electrode.

Having thus disclosed my invention and described an illustrative embodiment thereof, I claim as new and desire to secure by Letters Patent:

1. In a motor of the magnetic type having field windings and a rotary armature; a current interrupter including a flexible resilient rocker oscillated in timed relation to the movement of the armature, a metal enclosure carried by the rocker and arranged to take on a whip in the voscillations of the rocker, spaced contacts provided within the ends of the said enclosure and wired in circuit with each other, and a metal slug located between said contacts and having a transversely movable section arranged to maintain at all times electro-contact with said enent metal having a U-shaped end, a journal extending through both branches of. said end which thus supply a wide bearing for the arm for edgewise oscillation in a pre-determined plane, the arm having a half twist at an intermediate point in its. length and contact members carried at the end of the arm.

3. In a motor of the magnetic type having field windings anda rotary armature; a current interrupter including a rocker, an elongated metal enclosure carried thereby and having spaced electrodes, and an intermediate conductive member constructed and arranged to move longitudinally between said electrodes and having a section therein which is mounted for transverse movement and maintained at all times in contact with said metal enclosure.

4. In a motor of the magnetic type having field windings and a rotary armature; a current inter.- rupter including a rocker, and elongated metal enclosure carried thereby and having spaced field windings and a rotary armature; contact mechanism including a rocker arm of thin resilient sheet metal having a U-shaped end, a journal extending through both branches of said end which thus supply a wide bearing for the arm for edgewise oscillation, and means carried by said journal for maintaining one branch of the U-shaped end normally under yielding pressure.

JOHN A. HANLEY. 

